Patent GB-242891-A (GB)
Title: An improved machine for making paper bags
IPC: B31B29/00
Filed: 1925-05-16
Abstract: 242,891. Strong, A. G. O. May 16, 1925. Paper bags, making.-In a machine for making block-bottom paper bags, a paper blank, after being pasted, is drawn by grippers until it lies over a former-plate of special construction, round which it is folded to form a flattened tube, the former-plate being mounted to slide vertically on a horizontally-reciprocating carriage which also carries the folders for making the diamond fold in the bottom of the bag. The partly-formed bag is moved by rollers and reciprocating fingers into a position where it is gripped against a sliding plate whilst paste is applied to the bag bottom and the final folds are made by swinging fingers. The sliding plate then moves to deliver the bag to pressing-rollers. Feeding and pasting blanks. The blank to be operated upon is placed, automatically or by hand, upon a table 1, Figs. I and V, with the forward end of the blank resting against stopfingers 2 pivoted on the table. Cams 5 allow the table 1 to move downwards about hinges 3, and, during this movement, extensions on the fingers 2 strike a fixed bar 8, thus depressing the fingers 2 out of the way of the blank, which is then moved forward by intermittently-rotating rollers 9, 10. The upper feed-rollers 9 have a short vertical movement, and they descend to grip the blank just before the feed-rollers start to rotate. Pasting-rollers acting in conjunction with the feed-rollers apply paste for the longitudinal seam and the bottom seam. If no blank is present on the table 1, the feed-rollers 9 and the pasting-rollers are prevented from descending by pivoted catches 28 controlled by fingers 23 which normally bear on the blank, and are thus prevented from entering clearance slots in the table 1. Grippers 32, Figs. 1 and VII mounted on arms 33 projecting from a slide 34 engage the blank as it is delivered from the rollers 9, 10 and draw it over a former-plate 41 mounted on a horizontally-moving carriage 59. The jaws 35, 36 of the grippers 32 are normally pressed together by a spring, and are opened at the required times by fixed cam-surfaces engaging pins 38 39. A spring plate 40 passes the blank lightly against the bottom jaw 36 and prevents it from rebounding from stops that determine the limit of its movement. Tube forming apparatus. The former-plate 41, Figs I and IV, rises and passes the blank against a plate 45 slidably mounted on rails 46 and, at the same time, fingers 136, Fig II are moved forward so that they come in line with the sides of the former-plate and thus form practically continuous edges over which the paper is folded to form a tube by sliding plates 47, 48, Fig. IV, mounted on the carriage 59. The fingers 136 are then withdrawn from the paper tube. Forming the diamond fold and stripping the bag off the former-plate. The end of the paper tube is folded back over the end of the plate 45, Figs. I and II, by a cam-actuated pivoted finger 55, Figs. 1, II, IV, and XIV, which is mounted on the carriage 59 and engages in a slot in the shaped end of the former-plate 41. The correct rising of the triangular portion V, Fig. XIV, is ensured by an upwardly swinging pad (not shown) arranged to grip the paper against the edge of the former-plate. During these folding operations, the longitudinal seam in the bag tube is pressed by a cam-actuated plate. The diamond fold is completed by blades 73, 74, Figs. II and IX, pivoted on the carriage 59 and actuated by notched discs 77 engaging fixed pins 79, 80, and the gripper plate 45 is then moved by a lever 82, Fig. II, so as to move the bag partly off the former-plate 41. To facilitate this operation, the former-plate 41 may have a central cam-actuated portion 85, Fig. XII, which slides relatively to the carriage 59 and keeps the point of the partly folded bottom in shape until it is received by rollers 91, Figs. I and II, which draw the bag completely off the former-plate and pass it to presser rollers 93 arranged to deposit it on a table 94. Final pasting, folding, and pressing operations. Fingers 95, Figs. I and II, push the bag into the position R where the bag bottom is gripped againt a sliding plate 108 by fingers 104 which turn horizontally and have a rising and falling movement. Paste is applied by a vertically reciprocating paster 100 which swings horizontally to receive paste from a roller 116, and the triangular parts of the bag bottom are then folded over the fingers 104 by blades 101, 102. If no bag is present on the plate 108, a peg 122 on the end of a pivotal arm 118 enters a clearance hole in the plate 108 and allows a pivoted member to move into such a position that it blocks the downward movement of the paster 100. When the bottom folds have been completed, the sliding plate 108 carries the bag to pressing-rollers 103 which draw it off the fingers 104 and eject it from the machine.